Vehicle Coolant Circulation Control for Engine Warm-Up
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Solution Overview
Problem
Existing coolant circulation systems for vehicle-mounted internal combustion engines face challenges in preventing coolant boiling while effectively promoting engine warm-up, as the temperature of coolant is not uniform, leading to potential boiling in areas with higher temperatures than detected by the liquid temperature sensor.
Innovation Solution
A coolant circulation system that includes a motor-driven pump, a liquid temperature sensor, and a controller to execute circulation stop control based on temperature variations, determining whether the temperature difference is within a predetermined value, and adjusting the duration of circulation stop control to prevent boiling and ensure adequate warm-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the circulation stop control period is extended to promote warm-up, then the warm-up effect is improved, but the risk of coolant boiling increases
Solution Approach 1:
The controller performs variation determination control by driving the motor-driven pump during a predetermined period after engine startup to measure coolant temperature variation before deciding whether to execute circulation stop control. This preliminary action ensures that circulation stop control is only implemented when temperature variation is within acceptable limits, preventing coolant boiling while allowing extended circulation stop periods for effective warm-up when conditions permit.
2Reliability
If the determination value is reduced to prevent coolant boiling, then the boiling prevention is improved, but the warm-up promotion effect is reduced
Solution Approach 1:
The system uses feedback from coolant temperature detection to dynamically adjust circulation control strategy. The liquid temperature sensor detects coolant temperature, and the controller calculates temperature variation based on detected values. This feedback mechanism allows the system to extend circulation stop control period when temperature variation is small (improving warm-up) while automatically reducing the period when variation is large (preventing boiling), thus resolving the contradiction between warm-up promotion and boiling prevention.
3Device complexity
If the circulation stop control is executed based on single-point temperature detection, then the control simplicity is improved, but the temperature distribution uniformity is worsened
Solution Approach 1:
Before executing circulation stop control, the controller performs variation determination control by driving the motor-driven pump to circulate coolant and measuring temperature variation at the detection point. This preliminary action allows the system to infer coolant temperature distribution uniformity from single-point detection data, ensuring that circulation stop control is only executed when temperature distribution is sufficiently uniform, thus preventing boiling in undetected high-temperature zones while maintaining control simplicity.
Data Source
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AI summary
A coolant circulation system includes a coolant circuit (R10) including a water jacket (36, 45), a motor-driven pump (60), an outlet liquid temperature sensor (54), and a controller (100). The controller (100) executes variation determination control for driving the motor-driven pump (60) to determine whether a variation in the temperature of the coolant in a diesel engine is equal to or less than a predetermined value based on an outlet temperature detected by the outlet liquid temperature sensor (54). The controller (100) executes circulation stop control on condition that it is determined that the variation in the temperature of the coolant is equal to or less than the predetermined value. The controller (100) changes the period during which the circulation stop control is executed in accordance with the outlet liquid temperature detected at the start of the circulation stop control.